THURSDAY, April 12, 2018 (HealthDay News) -- The reasons students quit high school are complex, but aggression and weak study skills are two key factors, a new study finds.

Researchers followed 620 students in Georgia from grades 6 to 12. Teachers completed annual assessments of each student during that time.

For students with high levels of aggression and low study skills, the dropout rate was 50 percent. That compared to less than 2 percent among students with the lowest levels of aggression and the strongest study skills, the researchers said.

"What we find in our study is that the students who are dropping out have complex behavioral and academic problems," said study lead author Pamela Orpinas. She's a professor of health promotion and behavior at the University of Georgia's College of Public Health.

While the U.S. dropout rate has declined, many school systems still have large numbers of students who don't finish high school, the study authors noted.

It's important to identify and correct all behaviors that put students at risk of dropping out, Orpinas said in a university news release. "Simple and single solutions do not work," she explained.

While teachers can do little about events outside of the classroom that might cause students to quit -- such as problems in students' homes and neighborhoods -- Orpinas said aggression and study skills are issues that could potentially be managed in the classroom.

"Graduating from high school is almost like a miracle drug," she said. "If you think of one thing that we could do to improve students' health, it's make sure kids have a good education and graduate from high school."